Chapter 7
Long-Term Trends in Sulfur
and Reactive Nitrogen Deposition Across
the Northern Hemisphere and United
States
Rohit Mathur, Yuqiang Zhang, Christian Hogrefe and Jia Xing
Abstract We model the changes in wet and dry deposition amounts of reactive
nitrogen and sulfur over the 1990–2010 period using the WRF-CMAQ modeling
system. WRF-CMAQ simulations for this 21-year period were conducted over a
domain covering the northern hemisphere using a horizontal resolution of 108 km
and a nested domain over the contiguous U.S. using a grid of 36 km resolution. The
impacts of contrasting changes in emission patterns across the Northern Hemisphere,
i.e., reductions in North America and Europe vs. increases across regions in Asia, on
changing deposition amounts over terrestrial and aquatic ecosystems in these regions
is analyzed.
7.1 Introduction
A detailed understanding of the distribution and fate of atmospheric sulfur (SO x ) and
reactive nitrogen compounds (NO y and NH x ) is desirable given their role in determining tropospheric acidic substances and particulate matter budgets and potential
nutrient loading effects in sensitive ecosystems resulting from their atmospheric
deposition. The ultimate fate of airborne SO x , NO y and NH x is removal by wet
scavenging and dry deposition, which in turn lead to a variety of environmental
effects including altering net primary production, acidification, eutrophication and
other nutrient loading effects. The gas-particle partitioning of airborne sulfur and
reactive nitrogen regulates their transport distances since dry deposition velocity for
fine particles is relatively low, and consequently their primary atmospheric sink is
wet scavenging. Changing emissions patterns of NO x , SO 2 , and NH 3 have likely
altered both their atmospheric transport distances as well as deposition patterns and
amounts.
R. Mathur (B) · Y. Zhang · C. Hogrefe
Computational Exposure Division, National Exposure Research Laboratory, U.S. Environmental
Protection Agency, RTP, NC, Washington, D.C., USA
e-mail: mathur.rohit@epa.gov
J. Xing
School of Environment, Tsinghua University, Beijing, China
This is a U.S. government work and not under copyright protection in the U.S.; foreign
copyright protection may apply 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity, https://doi.org/10.1007/978-3-030-22055-6_7
41
Long-Term Trends in Sulfur
and Reactive Nitrogen Deposition Across
the Northern Hemisphere and United
States
Rohit Mathur, Yuqiang Zhang, Christian Hogrefe and Jia Xing
Abstract We model the changes in wet and dry deposition amounts of reactive
nitrogen and sulfur over the 1990–2010 period using the WRF-CMAQ modeling
system. WRF-CMAQ simulations for this 21-year period were conducted over a
domain covering the northern hemisphere using a horizontal resolution of 108 km
and a nested domain over the contiguous U.S. using a grid of 36 km resolution. The
impacts of contrasting changes in emission patterns across the Northern Hemisphere,
i.e., reductions in North America and Europe vs. increases across regions in Asia, on
changing deposition amounts over terrestrial and aquatic ecosystems in these regions
is analyzed.
7.1 Introduction
A detailed understanding of the distribution and fate of atmospheric sulfur (SO x ) and
reactive nitrogen compounds (NO y and NH x ) is desirable given their role in determining tropospheric acidic substances and particulate matter budgets and potential
nutrient loading effects in sensitive ecosystems resulting from their atmospheric
deposition. The ultimate fate of airborne SO x , NO y and NH x is removal by wet
scavenging and dry deposition, which in turn lead to a variety of environmental
effects including altering net primary production, acidification, eutrophication and
other nutrient loading effects. The gas-particle partitioning of airborne sulfur and
reactive nitrogen regulates their transport distances since dry deposition velocity for
fine particles is relatively low, and consequently their primary atmospheric sink is
wet scavenging. Changing emissions patterns of NO x , SO 2 , and NH 3 have likely
altered both their atmospheric transport distances as well as deposition patterns and
amounts.
R. Mathur (B) · Y. Zhang · C. Hogrefe
Computational Exposure Division, National Exposure Research Laboratory, U.S. Environmental
Protection Agency, RTP, NC, Washington, D.C., USA
e-mail: mathur.rohit@epa.gov
J. Xing
School of Environment, Tsinghua University, Beijing, China
This is a U.S. government work and not under copyright protection in the U.S.; foreign
copyright protection may apply 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity, https://doi.org/10.1007/978-3-030-22055-6_7
41